According to Mercedes PRO support, it is supposed to display the actual speed limit. They could find no setting or reason it would max out at 55. In fact, my MBUX worked fine displaying 70 on the freeway just 3 weeks ago...then something changed. The only thing I can think of would be a software update (over the air). Support considered it a problem but their recommendation to take it to the dealer is ridiculous. The dealer has one option - reflash the system. If this is a bug in the software, that won't fix it and they will have to contact the software team to address it. Once again, auto manufacturers treat everything as a mechanical/dealer issue. These cars are as much computer as mechanical now and the dealer cannot address software bugs.